How can I use arithmetic operations (for C pointers) using coder.opaque types?

Question

Marcel Vilalta i Soler 2017-5-12

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https://ww2.mathworks.cn/matlabcentral/answers/339978-how-can-i-use-arithmetic-operations-for-c-pointers-using-coder-opaque-types

回答： Marcel Vilalta i Soler 2017-5-15

Hello everyone,

I am into a project that uses coder.opaque to create char*, and I need memcpy to another another variable coder.opaque type, applying arithmetic operations to that "pointers".

Following I show you an example to explain what I am saying better:

first = coder.opaque('char*');
last = coder.opaque('char*');
def = coder.opaque('char*');
def = coder.ceval('(char*) malloc', 100);
% some operations %
memcpy(def, first+1, last-first); % Error. Expected either a <basic types>. Found a coder.opaque

How can I apply, or do the same, '+'/'-' operators to coder.opaque variables pointers, for move into the memory?

Regards,

Marcel

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Answer 1

Marcel Vilalta i Soler 2017-5-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/339978-how-can-i-use-arithmetic-operations-for-c-pointers-using-coder-opaque-types#answer_267092

Well,

I obtain a solution about this problem, but I am not very satisfied...., if anyone could do it better, please, share!.

In my case, I generate a C code, and with x=coder.opaque('char*', 'info+1'), when I use x on the parameters for coder.ceval() on the generated code it writes literally its value (info+1).

Regards,

Marcel